As an example, in the application of infrared transmitter IC, it generally needs a crystal (or resonator) for providing an accurate frequency to the IC circuit. Said crystal will be parallel connected with two pins of the infrared transmitter IC, and then both will be disposed on a circuit board. However, since the crystal occupies too much space, and the pin number of the IC can not be reduced, the infrared transmitter can not be further miniaturized.
Therefore, the present invention provides a new circuit form by putting an oscillating circuit into IC, so as to save the crystal space on the circuit board. Because of the progressing of IC technologies, an added oscillating circuit in an IC will not increase too much volume of the IC.
However, when an oscillating circuit is built in IC, the frequency accuracy thereof is very difficult to control, and solving this problem is therefore a major object of the present invention.
Furthermore, the internal power supply of a remote control circuit, e.g. a battery, will generally decrease with time; and transient current happened during turning on the output driving device (e.g. NPN BJT) will also produce too much noise, both will influence the oscillating frequency. These problems are also the targets of the present invention.